Formation of gear-wheel teeth.



c. A. PARSONS & s. s. COOK.

FORMATION OF GEAR WHEEL TEETH.

APPLICATION map JUNE 24, I916.

Pat ented Mar. 27, 1917.

' 2 SHEETS-SHEEI' I.

C. A. PARSONS & S. S. COOK.

FORMATION or GEAR WHEEL TEETH.

APPLICATION FILED JUNE 24. ISIS.

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one ates ALGERNON r'AnsoNs, or

TED STATES PATENT orrrcit'.

NEwcAsTLE-nPoN-Tvn'E, AND STANLEY SMITH COOK, G'F WALLSEND', ENGLAND; SAID COOK ASSIGNOR T0 SAID PARSONS.

FORMATION OF GEAR-WHEEL TEETH.

Be it known that we, CHARLES ALGERNON PARSONS, a subject of the King of Great Britain and Ireland, and residing at Heaton Works, Newcastle-upon-Tyne, in the county of N orthumberland, England, and STANLEY SMITH (3001:, asubject'of the King of Great Britain and Ireland, and residing at Tur-: binia I Works, Wallsend-on-Tyne, in the county of Northumberland, England, have invented certain new and useful Improvements in and Relating to the Formation of 'Gear-Wheel Teeth, of which the following is a specification.

This invention relates to the 'method of and means for forming the teeth of gear wheels such as are described in co-pending application Serial Number 756760 filed th March 1913.

Referring now to the accompanying diagrammatic drawings Figures 1 and 2 represent in elevation and plan respectively a portion of a gear cutting machine embodying the present invention and employing four driving worms, thesectional part of Fig. 1 being taken on the line AA Fig; 2.

Fig. 3 is a side elevation view illustrating a portion of the modified form of gear cutting machine embodying the present invention in' which two worm wheels, each with a single driving worm, are employed.

Fig. 4 is an end elevation of Fig. 3.

In carrying this invention into effect in a gear cutting machine as shown in Figs. 1 and 2, the shaft a (hereinafter'referred to as the driving shaft) carries two bevel wheels 6, 0,

The bevel wheel d engages with a bevel wheel I) and is mounted on a shaft 6 extending across the bedgof the machine. This shaft e' at its farther-end isprovided with a second bevel wheel fengaging with a bevel wheel' 9 mounted on a vertical spindle h which carries two worms of which only one, viz., z' is shown in Fig. 2.

Engaging jwith these latter worms are worm wheels 9' and j on spindleslc and k.

A similar arrangement is provided in connection with the second bevel wheel 0 on the driving shaft a. The bevel wheel 0 enga es with the bevel wheel m on the vertical sha t n which carries two worms 0 and 3 The worms 0 and y engage with worm wheels 12 Specification'of Letters Patent.

Original application filed March 25, 1913, Serial No. 756,760. Divided 1916. Serial No. 105,756.

. Patented Mar. 27, 1917.. and this application filed Julie 24,

which are .both of which wheels are attached to thetable If on which the work "11 is mounted. The worms on the vertical shaft h are similarly arranged to transmit their rotation to the table t through two worms engaging with the worm wheels 8' and 3 respectively. Only one of these latter worms, viz., 4, is visible in the drawings.

It will be seen that the rate of movement of the table t is controlled by the four worms and any irregularity in the movement of this table, the worms'or from irregularity in the teeth of either of'the worm wheels 8 or 3 passing in contact with one of said worms, is checked by the engagement of the other Worms with the worm wheels,

It. is desirable that the portion of the circumferential length along the pitch circle between the point of contact of the two worms with the particular worm wheel with which they are in"'engagement should not comprise exactly a whole number of tooth spaces, but should include a fraction of a tooth space so that these points of contact do not simultaneously correspond to similar parts of the teeth.

Also, it is in general preferred to place the individual worms of each pair of worms so that the circumferential distance between them is half a pitch distance greater or less than the half circumference of the worm wheel, so that their engagements are in opposite phase both as regards the period of rotation of the work and as regards individual teeth of the driven wheel. A

In some cases it may be necessary to provide springs .to obtain an approximately equal division of the driving force between the worms, but generally the natural elasticity of the shafts and supporting structure will be sufficient for this purpose.

As an example in the use of springs for this purpose, springs such as? may be 1nserted on either side of the worms which engage the worm wheels s and 3. When such arising from an irregularity in any of It will be understood that the springs are placed under an initial compression when in serted into place and that they abut on one side against the end of the worm and on the other against a fixed portion of the machine structure, such as the end of the bearing carrying the worm shaft, or a collar attached to the shaft.

In order to break the correspondence of the periodicity of the irregularities in the rate of movement of the table due to irregularities in any of the four worms, or in either of the worm wheels, the latter are preferably made with teeth of different pitch, the worms engaging with one worm wheel being, of course, of corresponding pitch. The worms engaging with one worm wheel will then have to be rotated at a different speed to those in engagement with the other worm wheel, and this difference of speed is suitably provided for in the means connecting the driving shaft a with the spindles on which the worms are mounted. The teeth of the worm wheels, 8 and 3, particularly when these wheels are made of the same pitch, may be interpitched circumferentially, by which we mean that the worm wheel a has double the number of teeth as the wheel 3, and this being the case there will be a tooth on wheel 8 opposite every space between the teeth on wheel 3, this being the arrangementillustrated in Fig. 1.

Only a single worm driving each of the worm wheels, 8 and 3, may be provided if desired, (see Figs. 3 and 4) these single worms rotating at the same or different speeds according as towhether the worm wheels, 8 and 3, are provided with teeth of similar or different pitch. In the form shown in Figs. 3 and at the teeth of the wheel a are of finer pitch than-the teeth of the wheel 3.

In this manner the angular movement of the work is made to register with the average configuration of the parent gear, and consequently the errors which would be introduced by any of the separate drives are eliminated or at least greatly reduced.

It will be seen that the relative position of the member forming the teeth and the wheel on which the teeth are being formed is determined by the general or average configuration of the members of the parent gear.

Having now described our invention, what we claim as new and desire to secure by Letters Patent, is

1. A gear cutting machine comprising in combination a work-table, a plurality of driven means attached to said table, and a plurality of sets of driving means, each of said sets engaging with one of said driven means.

2. A gear cutting machine comprising 1n combination a work table, worm wheels at-- tached to said table, a plurality of worms, said worms engaging with said worm wheels in pairs, and means between the worms of each pair to equalize the driving forces between them.

3. In a gear cutting machine, in combination, a work table, multiple driven means attached to said table, multiple sets of multiple driving means, each of said sets engaging with one of said driven means.

4. In a gear cutting machine, in combination, a rotatable work table, multiple driven means attached to said table, multiple driving means engaging with each of said driven means, and means to equalize the turning. moments upon the several driven means.

5. In combination in a gear cutting machine, a work table, multiple driven gearmeans attached to said table, all of said gear means having different tooth pitches and multiple driving means engaging with said driven means.

6. In combination in a geaneutting machine, a work table, multiple driveh gear means attached. to said table, all of said gear means having difi'erent tooth pitches, multiple driving means engaging with said driven means, and means for interconnecting said multiple driving means.

7. In combination in a gear cutting 'machine, a work table, multiple worm wheels upon said table, said worm wheels having different tooth pitches, worms engaging with each of said worm wheels, and interconnect- 100 ing means between said worms to transmit driving forces'thereto. I

8. In combination in a gear cutting machine, a work table, two driven gear means attached to said table, said gear means hav- 105 ing different tooth pitches, and multiple driving means engaging with each of said driven means.

9; In combination in a gear cutting machine, a work table, two driven gear means 110 attached to said table, said gear means having difl'erent tooth pitches, multiple driving means engaging with each of said driven means, and means for interconnecting said multiple driving means to transmit driving 115 forces thereto.

10. In combination in a gear cutting machine a work table, two form Wheels attached to said table, said worm wheels having difierent tooth pitches, multiple worms 120 engaging with each of said worm wheels, and interconnecting means between said worms to transmit driving forces thereto.

11. In combination in a gear cutting ma-. chine, a work table, two worm wheels upon 125 said table, said worm wheels having different tooth pitches, worms engaging with each of said worm wheels, and interconnecting means between said worms to transmitdriving forces thereto.

posite phase relation as regards the angularposition of their points of engagement with the worm wheels, and also as regards their points of engagement with the individual teeth of said wheels.

13. In combination. in a gear cutting ma-' chine, a Work table, multiple worm wheels l attached to said table, said worm Wheels hav-- ing diflerent tooth pitches, multiple worms 15 engaging with each of said worm wheels and said worms to transmit to the work table equal driving moments;

14. A gear cutting machine comprising in combination a work-table, a plurality of driven means'attached to said table; a plurality of sets of driving means, said driving means engaging with said driven means in pairs and means between said driving means of each pair to equalize the driving forces between them, substantially as described.

In testimony whereof, we have aflixed our signatures.

,CHARLES ALGERNON PARSONS.

STANLEY SMITH COOK.

diiterential interconnecting means between 

